47 lines
835 B
C++
47 lines
835 B
C++
//
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// Created by light on 20-1-7.
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//
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#include <iostream>
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#include <array>
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int sqr(int n) {
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return n * n;
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}
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int rand() {
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return std::rand();
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}
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// constant expression
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constexpr int sqr1(int n) {
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return n * n;
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}
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constexpr int factorial(int n) {
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// n是普通的int 不能使用static_assert
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// static_assert(n>=0); //error
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// 正确方式
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if (n < 0) {
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throw std::invalid_argument(
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"Arg must be non-negative");
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}
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if (n == 0) {
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return 1;
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} else {
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return n * factorial(n - 1);
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}
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}
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int main() {
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int a[sqr(3)]; // ok
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const int n1 = sqr(3); // ok
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constexpr int n = sqr1(3); // constexpr=constant expression 常量表达式
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std::array<int, n> aa; // ok
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std::array<int, factorial(10)> b; // ok
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int cc[rand()];
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return 0;
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} |